Cathode ray tube



Oct. 19, 1937. w. H. PAINTER CATHODE RAY TUBE Filed May 21, 1936 INVENTOR W. H PAINTER wmo',

ATTORNEY Patented Oct. 19, 1937 I GATHODE RAY TUBE William H. Painter, East Orange, N. J assignor,

by mesne assignments, to Radio Corporation of America, a corporation of, Delaware '1 Application May 21, 1936, Serial No. 80,926 a I e came. (01. 250-215) :3; My invention relates to electron discharge tubes and more particularly to themounting of electron :beamfgenerating;focusing and accelerating electrodes to form :a cathoderay gun for electron discharge devices. of the cathode ray 'type; 1

.In conventionalcathojde ray tubes the cathode raygun for producing the cathode ray or beam "of electrons comprises .a'thermionic cathode and 1 various aperturedrcbldelectrodes mounted on a lglassipress" or pinch by metal support wires or rods. Accuratezandpermanent alignment of the {electrodes which is necessary for efficient and stable operation, has been obtainablein the con- 15 ventional cathode raylgun only with difficulty and "by assembly methods which are slow and re- :quire a: considerable amount of skilled hand Oneobject of my invention is toprovide an improvedcathode ray gunof greater rigidity and fbetter alignment of the electrodes than'is found *ir'i'the conventional devices of the kind.

, i'iAnother object is to provide a simplified and improved method :of assembling the electrodes 7 into a:=rigid Eand accurately aligned cathode ray .gun.

"Other objects andadvantagesof my invention 'will appear from the following description of the invention; J 5

The novel features that I consider character- Fist'ic of my'inven'tion together with the'invention itself will best be understood a from the following description of certain preferred embodiments thereof when read i n connection with the accom- L35 partying"drawing in which:

- Figure iljis' a view in side elevation of a cathode raytube with a cathode ray gun embodying one -form of my invention;

7 Figure '2 isaperspective view of the mount;

vs40 Figure 3 is a longitudinal sectional view of the gc'athode ray electrongun' ofthe tube shown in Figure '1;"and g I -F'i guree 'is" a pe'rspective view of a portion of the cathode raygun and deflection structure,

The cathoderay tube shown in the accompanying drawing-is 'in gerieral of the conventional type. The evacuatedbulb ID has a fiuorescent "screen at the: large means at the other end a "tubular neck'which contains a mount comprismg :a" tubular glass stem H with an annular press" I2, and a cathode raygun, in general of 'the conventional type, carried by the stem. -Suitable cathode 'r'ay'deflection elements may be "provided such asithe deflection p1ates 8 and 9, e55or electroemagnetic means or a combination of both, may be utilized to deflect the electron beam as it passes from the cathode ray gun to the fluorescent screen. The cathode ray gun comprises the usual indirectly heated cathode l3, .withcooperating cold electrodes such as the controlgrid I l, and first and secondtubular anodes l5and. l6, axially aligned with' the cathode and .with one another. These electrodes may be conductively connected to lead wires sealed in the press. by suitable conductors l1, l8, I9 and 20 respectively. Certain of these conductor'leads may also serve :as mechanical support members as hereinafter stated.

' .Accurate alignment of the first and second anodes withthe control grid is essential for the a proper operation of the tube, and this alignment should be maintained in use inspite of temperature variations in the electrodes of the cathode ray gun. A common way of holding the electrodes in alignment 'is to'provide glass rods 01' pedestals extending from the stem with projectmg support wires'and to weld the projecting ends of these wires-to the electrodes while the eletrodesare held in alignment on a mandrel or in a jig. This method of assembly is l relatively slow, requires considerable hand work and skill, and experience has shown that in such a cathode ,ray gun the electrodes are apt to move out of alignment slightly either just'subsequent to as- .sembly due to inherent strains in the parts or during use of the tube.

In accordance with my invention I maintain the coldelectrodes', such as the control grid, the first anode, and the second anode,'in rigid and "permanent alignment by providing each of these electrodes with rigid radial projections, which is conveniently done by attaching, preferably by welding to each of the three electrodes several support'brackets 2| which project radially outward beyond the periphery of the electrode.

.When the electrodes are in place the projections or brackets on each electrode are aligned with the corresponding projections on the other electrodes to form as manyrows of projections as there are projections on each electrode. In the tube shown in the drawing there are three projections on each electrode, and therefore three rows, each row containing three projections, one on each of the three electrodes. The projectionsor brackets in each row are firmly secured to a pair of parallel support rods which extend lengthwise of the electrodes and may be of any rigidinsulating material, preferably of -=g1ass or :similar vitreous material which maybe by pinching on both sides of the bracket and are thus sealed to each other and to the support bracket between them. Preferably, as shown in the drawing, three pairs of glass rods are, used to rigidly tie together in proper alignment the control grid to the first and second anodes. This mounting is inherentlystrong, as any tendency of a rod to bend in a plane tangent to the anodes is opposed by the companion rod of the pair, while bending or tilting'movement of the anodes is' opposed by the pair of rods on'the other side of the mount.

I have obtained good results and secured strong and rigid mounts in which the electrodes remain accurately aligned during use by using for the brackets nickel which has been fired in hydroen at about 1200 C. for about 15 minutes and using rods of lime glass which will make a strong seal with suchnickel brackets. In these mounts lass rods about 0.1 inch in diameter were used and the electrodes as well as the rods were held in a jig during the assembly of the mount. If

desired, the glass tie rods can be extended and joined to the press of the stem, but ordinarily it is suificient to rigidly tie together by the structure such as I have described the control grid and the first and second anode- Such a mount is considerably stronger mechanically than the mounts heretofore made and will withstand considerable pressure without either breaking or causing mis-alignment of the electrodes. Two pairs of mounting rods will ordinarily give satisfactory results, but in general I prefer to use, as shown in the drawing, three or more pairs to give ample strength. 3 V

I have at timesfound it desirable tosupport the cathode ray deflection electrodes directly on the electron gun structure which procedure insures perfect'alignment of these electrodes with the focusing members of the electron gun. Figure 4 shows such a structure in which the glass rods 22 are sufiiciently extended to provide support for the electrodes 8 and 9 through additional brackets ZIA. The method of assembling the'part's'of the electron gun and deflection structure in accordance with my invention is not only much simpler and quicker than the conventional methods heretofore used, butioffers advantages in production because it is adaptable to machine operation.

The parts mounted in a jig can easily be carried :while in the jig through a machine in which the heating of the glass rods adjacent the brackets and the pinching of the glass rods down on the brackets to seal the pinched portions to each other and to the bracket can be carried out with great expediency.

What I claim as new and desire to secure by 7 Letters Patent is:

g l. A cathode ray gun assembly including a pluralityof axially aligned cylindrical electrodes, a bracket on each of said electrodes extending radially beyond the periphery of theelectrode, the brackets on said electrodes being aligned in a.

row, and a pair of glass support rods positioned side by side along and on opposite sides of the row of brackets, with the portions adjacent each bracket sealed to each other and to the bracket and the portions intermediate the brackets spaced apart in a plane perpendicular to the bracket.

2. A cathode ray gun assembly including a plurality of axially aligned tubular electrodes each having a plurality of outwardly extending radial projections uniformly spaced on the periphery of each electrode, the projections on each electrode being aligned with the corresponding projections on each adjacent electrode to form a plurality of rows of projectionsv parallel to the-longitudinal axis of said electrodes, and a pair of glass support rods extending along each row o1 projections on opposite sides of said projections, the portions of said rods of each pair adjacent each projection being sealed to each other and to the projection and the remaining portions being spaced apart and theprojection. g I 3. A cathode ray focusing and defiectionassembly including a plurality of axially aligned cylindrical electrodes and a plurality of substantially plane electrodes, a bracket on each of said electrodes extending radially beyond the periphery of the electrode, the brackets on said'electrodes being aligned in a row, and a pair of glass support rods positioned side by side'along-and on opposite sides of the row of brackets, with the portions adjacent each bracket sealed to each other and to the bracket andLthe portions inter mediate the bracket spaced apartin a planeperpendicular to'the bracket. 1

4. A cathode ray tube including an evacuated envelope having a stem at one end and a fiuorescent screen at the other end, and a cathode ray gun directedtowar'd said screen and mounted on said stem and comprising a cathode, a plurality of tubular electrodes axially aligned with said cathode and with one. another, a plurality of projections extending radially beyondthe periphery of each electrode with the projections on parallel to a plane tangential to said electrode at eachelectrode aligned in a. row with'the corresponding projections on the other electrodes. and two vitreous rods positioned side byside along each row of said projections and sealed'at each projection in the row to each otherland :to

the projections.

jections extending radially beyond the periphery of the electrode with the projections onreach electrode aligned in a row with the correspond;-

ing projections on the other electrodes and 'two vitreous rods positioned. side by side alongeach row of said projections and sealed'at each projection in the row tov each other" and to the projection.

6. A cathode ray tube including an evacuated envelope having a stem at one end, a fluorescent screen at the other, and a plurality ofraydefiection plates therebetween, and a cathode ray gun directed toward said screen and comprising a cathodemounted on said stem, a tubular electrode adjacent said cathode rigidly supported by said stem, at least one additional tubular'electrode in alignment with said.- first electrode each and two vitreous rods positioned side by side of said tubular electrodes and said deflection along each row of said projections and sealed at plates having projections extending beyond the each projection in the row to each other and to periphery thereof With the projections on each the projection.

5 aligned in a row with the corresponding projec- WILLIAM H. PAINTER. 5

tions on the other electrodes and deflection plates 

